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New research, as presented at the 2017 ATS International Conference, found that patients with obstructive sleep apnea (OSA) are at a higher risk of developing atrial fibrillation (AF or a-fib).
Obstructive sleep apnea is characterized by symptoms of repeated events of shallow breathing with occasional cessations of breath during sleep. These events cause decreased blood oxygen levels and severely disrupt sleep patterns. A-fib is a heart arrhythmia characterized by an irregular or fast heartbeat, which can lead to heart problems and stroke.
Lead author of the study and assistant professor of medicine at Canada’s University of Ottawa, Dr. Tetyana Kendzerska, notes that the findings indicate there are strong biological connections linking OSA with increased risk of a-fib through a variety of mechanisms. The evidence suggests that these mechanisms include metabolic abnormalities, cardiac stretch, sympathetic activity, and oxidative stress.
The research team in Canada analyzed medical records for 8,256 adults with an average age of 47 years, who were suspected of having sleep apnea but did not have any known diagnosis of heartrate fluctuations or abnormalities, including a baseline a-fib. Patients were followed for a total of 13 years, during which time 173 patients developed atrial fibrillation that led to hospitalization.
Researchers measured the severity of OSA to see if there were significant predictors to a-fib by looking at a couple of elements:
- The number of events the patient had per hour of sleep, with events defined as partially or completely stopping breathing.
- Time spent with oxygen saturation below normal levels (<90%) during sleep.
After this process, they controlled for already established risk factors for a-fib.
Patients who developed a-fib were current or former smokers, have several other diagnoses, and were older. These and other risk factors were adjusted for in this research and the scientists found that desaturation during sleep continued to be a significant predictor of hospitalization for a-fib. This is just about oxygen saturation, not the number of breathing cessation events the individual had. Additionally, women were more likely than men to have a correlation between oxygen desaturation and hospitalization for a-fib.
Dr. Richard S. Leung, senior author of the research and assistant professor of medicine at the University of Toronto in Canada, notes that prior research shows us that women with OSA are at higher risk of heart disease and mortality. An explanation for this, he notes, is endothelial dysfunction, a higher likelihood of developing systematic and pulmonary hypertension, as well as impaired heart rate responses. However, additional research is necessary to confirm these findings and look at other potential mechanisms to the association.
The primary analysis did not include any mention of hypertension. They note that this may be the cause or link between a-fib and OSA, so having it as part of the analysis would have diminished the association. The secondary analysis, however, did add a control factor for hypertension, which continued to show a significant link between a-fib and oxygen desaturation. This indicates that hypertension may be an intermediate step between OSA and a-fib.
There were a few limitations in this research, including having no data on CPAP adherence, which is the standard treatment for OSA. Additionally, there was no information on whether the person’s hypertension was diagnosed and being treated. Additional research is being performed by the researchers to connect emergency room visits for a-fib and an OSA diagnosis.